1. Field of the Invention
The present disclosure generally relates to electronic circuits and, more specifically, to circuits executing digital data ciphering or deciphering functions.
The present disclosure more specifically applies to the protection of the execution of a ciphering or deciphering algorithm against attacks by fault injection.
2. Discussion of the Related Art
Ciphering algorithms are increasingly used in data processing and, in particular, to transmit data from one electronic equipment to another, be it for bank data (chip cards to be used with payment terminals), for the provision of multimedia data (toll television), the transmission of data over the Internet between several computers, etc.
The robustness of ciphering algorithms is likely to be put at risk by hackers attempting to discover the ciphering keys or, directly, the data. A category of so-called fault-injection attacks comprises disturbing the execution of the algorithm to deduce therefrom, by statistical analysis, the manipulated keys or data.
Countermeasures consisting of detecting a possible jump (caused by the injection of a fault) in the execution of an algorithm have already been provided. However, this detection is itself detectable by a hacker, for example, by analysis of the circuit power consumption. Further, the detection is dedicated to a specific behavior (detection of a jump). Moreover, most attacks are repetitive since they are based on a statistical analysis and countermeasures generally block the circuit, which can be detected by the hacker.